Backing Up In Linux

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There are currently three main types of
tape drives available for the PC (and hence Linux). There are those
based on SCSI interfaces, those based on the floppy drive interface
(QIC-40, QIC-80, QIC-117, QIC-3010 and QIC-3020), and QIC-02 type
drives. A new breed of tape drives that attach to the IDE interface
is coming, but at the moment, Linux support is minimal. There is no
Linux support for drives that attach to the parallel port.

You cannot simply attach a tape drive to your machine and
expect Linux to automatically recognize it. You need to tell the
kernel about it, and this can involve recompiling the kernel. In
addition, you need entries in your /dev directory so that programs
under Linux can access the tape drives.

Below, I will describe how to set up the two most common
types of tape drives.

Floppy Interface Tape Drives

Tape drives that connect to the floppy drive interface have
the advantage that no separate interface card is required; they
are, therefore, fairly cheap and reliable. Thus, this breed of tape
drive has been very popular.

One of the first tape drives of this type was the Colorado
Jumbo 250. The tape drive cable for these drives attaches to the
floppy drive interface. The QIC-80 specification defines how to
access these tape drives. Many other tape drives, including the
Iomega 250, Conner C250MQ, Wangtek 304, and Colorado Jumbo 350 are
QIC-80 compatible.

Tape drives that use the QIC-80 specification require a
program (actually, a “Loadable Kernel Module”) called
ftape, written by Bas Laarhoven and Kai
Harrekilde-Petersen, which at the time of writing is at version
2.03b. QIC-117 and QIC-40 formats are also supported by ftape, as
is QIC-3010 and QIC-3020 (i.e. QIC-WIDE) in an experimental form. A
complete list of tape drives supported by ftape can be found in the
vndors.h file in the ftape source distribution. Support for some
enhanced controller boards is also provided—specifically Iomega
Tape Accelerator, Colorado FC-10, and Mountain MACH-2. Support for
the FC-15 and FC-20 high speed Colorado controller boards is not
yet provided.

Most Linux distributions include ftape; if yours doesn't, you
will have to download it (see
Tape Resources
sidebar). Unless you are using module version support in
your kernel (if you don't understand what this means, you can
assume that you are not using it), ftape will need to be recompiled
each time you update your kernel.

Compiling ftape

First, go to your source directory and unpack the
sources:

:$ cd /usr/local/src
$ tar xzf ftape-2.03b.tar.gz

You will end up with a directory ftape-2.03b; all the ftape
source files will be in this directory along with some
documentation files. You now need to compile ftape to end up with a
file ftape.o:

$ cd ftape-2.03b
$ make clean
$ make dep
$ make all

Next, you need to make sure that your kernel has been
compiled with ftape support built in. Recompiling the kernel is
beyond the scope of this article (see the Kernel-HOWTO more
details), but basically, do:

$ cd /usr/src/linux
$ make config

to accept all the default values for all options (unless, of
course, you do want to change them), and when
you get to the QIC-117 option, answer Y. Leave
the NR_FTAPE_BUFFERS at the default value of 3.
Then recompile the kernel (usually make clean dep; make
zImage) and install the new kernel. Don't forget to
re-run lilo if you use it.

If you are using very recent kernels (1.3.30 and above), you
will have to use zftape. zftape (written by
Claus Heine) is based on ftape but provides support for the
dynamically loaded buffers provided by the later kernels. You
compile it exactly the same way as ftape. Installing it is also
done the same way as with ftape, except that you will use the name
zftape instead of ftape. When configuring your kernel, you will not
get asked any questions about QIC-117 options or
NR_FTAPE_BUFFERS.

Even if you are not using recent kernels, zftape provides
some very good enhancements over the basic ftape package, including
software compression, and it is well worthwhile upgrading to get
it.

Making The Devices

Next, you need to make sure that the /dev entries have been
created correctly for ftape. Once again, if you have a Linux
distribution, this will more than likely have been done, otherwise;
you will have to create them manually. Do:

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